1. Field of the Invention:
This invention relates to improvements in oil well pumps and more particularly, but not by way of limitation, to a reciprocal subsurface oil well pump of a minimum length and stroke for an efficient pumping operation.
2. Description of the Preferred Embodiment:
In producing oil wells it is common practice to provide a pump at the bottom of a well bore, or at least down the well bore in the proximity of the producing subsurface formation. The pump is normally secured to the lowermost end of the sucker rod string, which extends longitudinally through the well bore from a reciprocating device at the surface of the ground. The reciprocating device at the surface is usually a horsehead type apparatus and alternately raises and lowers the string of sucker rods in the well bore. Subsurface pumps have long presented problems in the lifting of the well fluid to the surface of the ground in that the plunger of the pump is usually several feet long and thus requires a relatively long stroke for operation of the pump. This results in substantially great friction and drag on the pump as the pump plunger reciprocates within the working barrel. As a result, the pump may not move freely and the plunger may not have a full stroke, thus reducing the pumping efficiency. In addition, since most of the subsurface pumps are relatively long, it may require several strokes of the pump before a sufficient load is applied to the pump for starting the pumping action. Also, many well fluids contain sand and other foreign particles which hinder the operation of the subsurface pump and frequently damage the working parts thereof.
In order to overcome these disadvantages, the pump shown in may aforementioned prior U.S. Pat. No. 4,229,149 was developed, and comprises a relatively short plunger or housing, as for example, ten or twelve inches in length, and which is threaded at one end for connection with the lowermost sucker rod for reciprocation thereby within the working barrel. The housing is open at one end for receiving the well fluid therein, and a ball check valve is carried by the housing for intermittently admitting the fluid into the fluid passageways of the housing whereby the well fluid may be lifted to the surface of the well. This pump has certain disadvantages, however, in that the sealing members interposed between the outer periphery of the housing and the inner periphery of the working barrel have proven to be a problem in the operation of the pump, and the stop means for limiting the upward movement of the ball member is frequently damaged by the force with which the ball member strikes the stop.
To overcome the disadvantages of the pump shown in my U.S. Pat. No. 4,229,149, I developed the pump shown in my U.S. Pat. No. 4,395,204. Whereas the second pump embodium ent is an improvement, the sealing members between the outer periphery of the pump housing and the working barrel are still somewhat of a problem, and the particular design of the ball stop members showed some disadvantages under actual prolonged use of the pump.